Tumor necrosis factor and related cytotoxins show considerable promise for their eventual exploitation in cancer treatment. Much needs to be known about the mechanism(s) of action, biochemistry, pharmacology, control of production by effector cells, and their interactions with each other and with other biological response modifiers such as interferons and interleukins. Since many of these molecules are now available in purified form due to recombinant technology, much progress can now be made. It is now timely and important to have an open and international meeting which should expedite further research and development and to coordinate, disseminate and exchange new information at a faster rate than can be done with publications in scientific journals. Results of the first clinical trials, from the USA, Japan, Europe and possibly elsewhere, should be available at the the time of the conference. The conference will also enable people working with these molecules and with the producing cells to become acquainted with each other, many for the first time, and to exchange ideas and information and, hopefully, to establish collaborations.